Best practices for installing air source heat pumps

Best practices for installing air source heat pumps

The number of air source heat pump installations taking place each year is increasing and more qualified heat pump installers will be needed if future heat pump installation targets are to be achieved. It is important than any engineer looking to work with heat pumps is suitably trained to ensure that the systems they install are correctly fitted and commissioned to provide their customers with years of reliable, low carbon heating. This blog talks through some of the key stages of the installation process.

As with any heating system, an air source heat pump installation follows a set of procedures which are detailed in the supporting Installation and Servicing Manual which engineers must follow. With a heat pump installation, the beginning of the process starts with the planning and thorough site surveys and assessments of the property and its heating and hot water requirements. Every home will have different requirements and it is important that installers work closely with their customers to ensure they specify and install a heat pump system which will fulfil their requirements.

While every installation will have its own specific needs, there are considerations that apply to all air source heat pump installations and we are going to explore some of these key steps to help heat pump engineers learn more about installing air source heat pumps.

  • Planning a heat pump installation
  • Equipment needed for a heat pump installation
  • On-site with a heat pump installation

Interested in completing heat pump training with the Grant Training Academy? Discover more about our heat pump course.

Air source heat pump installation process

As mentioned above, every installation is different and the process of installing an air source heat pump will vary especially between new builds and retrofits, but any heat pump installation should always involve these key steps:

  1. Pre-installation planning – this includes carrying out a thorough site survey and accurate room by room heat loss calculation of the property, discussing with the customer their requirements and specifying the products needed for the installation based on the design of the heating system.
  2. Installation – every heat pump should be installed in accordance with the manufacturer’s Installation and Servicing instructions. A typical heat pump installation may take longer than a boiler replacement and this is usually because it involves more installation steps and system checks. All new or replacement emitters selected such as radiators and underfloor heating will need to be sized and installed correctly for use with a heat pump to ensure the required heat output is achieved. All system pipework must be sized, fitted and lagged correctly, and the heat pump and heating and hot water system needs to be comprehensively set up and commissioned.
  3. Post-Installation – a pivotal part of any heat pump installation is the customer handover. Once the heat pump has been successfully installed and commissioned, the installing engineer should carry out an in-depth handover with the end-user so that they are familiar and confident with how their new heat pump heating system operates. Watch our Customer Handover videos here.


Equipment required to install an air source heat pump

When it comes to installing an air source heat pump, alongside the heat pump, accessories and core components needed for the system itself, engineers also need to remember the following:

  • Pipework insulation – insulating all internal and external system pipework with a suitable grade of insulation is vitally important. Grant UK supply a through wall insulation kit which includes a heavy duty insulation to fit through the wall of the property and around the flexi hoses connected to Aerona³ heat pumps. If all system pipework is not suitably insulated, this will negatively impact the performance of the heating system.
  • Electrical wiring – the installation of a heat pump does involve the installation of electrical wiring so the installing engineer needs to be suitably trained and competent to complete these elements of the installation work or a qualified electrician may be required at various stages of the installation process.
  • Specialist access equipment – if a heat pump is being wall mounted, additional equipment may be required depending on the maximum installation height of the heat pump specified by the manufacturer. To facilitate safe working, equipment such as scaffolding and suitable ladders may be required. All Grant Aerona³ R32 heat pumps can be wall mounted at a safe height, with the top of the unit no more than 2 metres above ground level.

Preparation required to install an air source heat pump

Prior to commencing an installation, installers should thoroughly assess the following:

Heat pump location

All heat pumps will make a noise and create a cold air discharge. It is important to discuss this potential nuisance factor with the end user when considering the final position of the heat pump. Taking the proximity of neighbouring properties into account as well as the heat pump position when opening doors and windows on the customer's own property. Where possible, choose a position which is protected from the wind and where the unit will not obstruct access to doors or paths. The orientation of the heat pump should also be considered – to ensure maximum efficiency, ideally a heat pump should be positioned on a warmer side of the property, preferably on a South facing side.

Suitable installation base

An air source heat pump must also be installed on a firm, flat, level surface. The surface on which a heat pump is fitted must be able to support the weight of the heat pump unit and minimise the transmission of noise and vibration. If a suitable surface is not already in place, installers will need to prepare a suitable base for the heat pump prior to installation by either laying a flat trowelled concrete base 150mm thick or by positioning paving slabs on compacted hard core of sufficient depth.

Clearances around the heat pump

Suitable clearances must also be in place around the heat pump – for Grant heat pumps, the recommended clearances are detailed in the Installation and Servicing Manual. These clearances are important because they allow for the adequate air flow in and out of the heat pump while also making the heat pump easy to access for commissioning, servicing and maintenance.

Assessing the electrical system

When planning a heat pump installation, an assessment of the existing electrical system at the property should be undertaken to confirm its suitability. Furthermore, with every heat pump installation on a premises, there is a requirement to inform the relevant Distribution Network Operator (DNO) – this can either be done via a DNO application (Apply to Connect) or a DNO notification (Connect and Notify). With Grant’s Aerona³ 6kW, 10kW and 13kW heat pump models, they are DNO approved which means that installers can, in most instances, notify the DNO retrospectively within 28 days of installation. With heat pump units which are not DNO approved, an application must be made to the DNO before connecting the heat pump to the mains electrical supply.

Choosing the right size air source heat pump

Specifying the correct size of heat pump is essential to ensure that the heating and hot water system perform correctly and efficiently. Please visit one of our other blogs to read more about specifying and sizing a heat pump system.

Installation best practices

We have collated a few of the top tips for good heat pump installation practices here but for more in-depth training, please enrol onto one of Grant UK’s in-person or online heat pump training courses.

Start with good design

We have mentioned it before but every heat pump installation should start with the planning, design and specification of the heating system. It is essential that the full layout of the system is understood before the installation of any components is undertaken. A heat pump installation involves a lot of technical considerations so taking the time to correctly design the system beforehand will make the installation easier and help ensure your customers are left with a correctly installed and efficient heating system.

Location and positioning

Make sure the heat pump is securely fixed on top of suitable anti-vibration mounts as well as ensuring that all of the recommended clearances are achieved around the unit. It is also important to position the heat pump controller in line with the guidance given in the installation and servicing instructions. Also ensure that all safety requirements have been complied with.

Water circuit pipework and appliances

This is a large part of an installation and should involve checking or completing all of the following. The water connections should be made tight and secure. A suitable in-line filter should be correctly installed. The pressure gauge should be correctly installed on the sealed system pipework or expansion vessel manifold. Connection pipes should be suitably supported. The expansion vessel should be suitably sized to accommodate the system volume. A volumiser tank should be installed unless there is a buffer, thermal store or combined buffer/cylinder is connected to the heat pump system.

The complete heating system should be thoroughly flushed out, this is especially important when a heat pump is being installed on an existing system. After flushing a suitable thermal fluid should be used to fill the system. Any Legionella protection installed on the system should be set up based on a risk assessment of the customer's vulnerability. All system pipework should be suitably insulated, and a flow regulator should be fitted on the return pipe to the heat pump to ensure that the required flow rate is achieved and maintained through the heat pump at all times.

Electrical connections

All electrical work must be undertaken by a competent person and installed as outlined in the installation and servicing manual. A dedicated power supply with a correctly sized breaker must be used, with the final power supply being made from a weatherproof lockable isolator located outside of the building.

Check the refrigerant

Grant Aerona³ R32 air source heat pump are all air-to-water and a monobloc design where the refrigerant is pre-charged into the unit during the manufacturing process. Any work that is required on the refrigerant circuit, must only be carried out by a competent person that holds the relevant F-gas qualification.

Ensure clear drainage

Heat pumps can produce several gallons of condensation every day depending on the level of humidity and usage. On the underside of the Aerona³ R32 heat pump, there is a condensate outlet that allows any condensate to drain from the heat pump and it is the installing or service engineer’s responsibility to ensure that provision is made to safely collect and dispose of this condensate. It is essential that this condensate is not allowed to run onto paths or driveways as this will turn to ice during the winter.

Follow manufacturer instructions

As previously mentioned, during any installation work, the manufacturer’s Installation and Servicing instructions should be adhered to. The latest installation manuals for Grant’s products can be downloaded from our online Customer Support Centre or via the TechBox app.

Become a G1 Air Source Heat Pump Installer with Grant UK

If you are interested in joining Grant UK’s G1 Installer Scheme for air source heat pumps, you will need to fulfil the requirements which includes heat pump product training. The Aerona³ air source heat pump training courses delivered through the Grant UK Training Academy and eLearning Academy have been developed to give installers and heating engineers the necessary knowledge and skills they need to install and maintain air source heat pumps correctly and safely.

Please learn more about our Training Academy here.

Steve Ellison
Assistant Training Manager at Grant UK

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